The disclosed invention relates to lasers, and is particularly directed to a high efficiency transverse discharge excitation laser having a narrow electrode structure.
Developments in laser technology have resulted in and the increased utilization of lasers in different fields, including industrial military and medical applications. The increased utilization of lasers has also provided further incentive for the continued development of lasers. As is well known, there are different types of lasers, and the subject invention is directed to gas discharge excitation lasers.
A traditional cavity excited gas laser includes an elongated cavity containing a discharge gas and electrodes at or near the ends of the cavity for providing a longitudinal electric discharge of the gas. The disadvantages of such longitudinal discharge excitation are well known and include the requirement of relatively large DC voltages along with the necessarily large power supply circuitry.
A further development of cavity excited gas lasers is the transverse discharge excitation laser wherein an RF excitation electric field is applied transverse to the longitudinal dimension of the excitation cavity. An example of such transverse discharge excitation laser is set forth in U.S. Pat. No. 4,169,251, issued to Laakmann on Sept. 25, 1979, and assigned to the assignee of the present invention. In the system of U.S. Pat. No. 4,169,251, the electrodes form two opposing walls of the laser cavity.
Characteristics of known transverse excitation lasers include low efficiency, the requirement of high power loading which may result in excessive laser gas temperatures, and limited mode control. As a result of such characteristics, known cavity excitation lasers may be physically large, tend to require large power supplies, and/or may have reduced operating lifetimes. The characteristics of known cavity excitation lasers are important considerations which may make them inappropriate for some applications.
With known transverse excitation lasers, control of operation to the desired lowest order could be achieved by reducing the dimensions of the cross section of an elongated excitation cavity. However, such reduction in cross sectional dimensions requires more complex and expensive manufacturing since the tolerances become more stringent. Also, power output is reduced and limited, and efficiency is reduced.
Another disadvantage of known transverse excitation lasers is that beam size is determined to a large extent by cavity dimensions, which requires substantially different structures for different beam sizes.